Direct drive reciprocating pump

ABSTRACT

The invention includes an apparatus for pumping a fluid through a reciprocating pump. Several motors are responsible for operating the pump assembly. Each of the motors has a drive shaft. The motor drive shafts are connected to a series of drive gears. The drive gears are operably connected to a single driven gear for rotating the driven gear. The single driven gear connects with the pump assembly and drives the reciprocating pump in order to force fluid through the reciprocating pump.

RELATED APPLICATIONS

[0001] This application claims the benefit under Section 119(e) of U.S. Provisional Application Ser. No. 60/466,715, filed Apr. 30, 2003, titled “Direct Drive Reciprocating Pump.”

FIELD OF THE INVENTION

[0002] The present invention relates generally to reciprocating pumps, and more specifically to the drive assembly of an oilfield mud or service pump.

BACKGROUND OF THE INVENTION

[0003] Various kinds of pumps have been used in oilfield operations. Two examples of pumps are a well service pump and a mud pump. Well service pumps are used for pumping cement or chemicals into the well and are typically mounted on a skid or a truck. Well service pumps typically operate in short time intervals, and are repeated later after servicing. Mud pumps circulate drilling mud down the borehole during drilling. Mud pumps typically operate in a continuous manner without interruption. Mud pumps also typically have a longer stroke, for which reason mud pumps tend to have a larger size and weight.

[0004] One prior version of a mud pump has two electric motors, a belt, or a chain, or a single drive shaft and gear, with each electric motor having a separate drive train. In this manner, prior mud pumps were typically fairly large in size. In other prior mud pumps, a gear unit is positioned inside the pump unit rather than on the outside of the pump unit. Because the gear unit was positioned inside the pump unit, such prior versions of mud pumps were not compact in size and were also of considerable weight. Mobile service pumps normally have only a single motor, which is located on one side of the pump. It has long been a desire to reduce the size and weight of oilfield service pumps and oilfield mud pumps, without sacrificing capacity. This is particularly desirable for mobile pumps mounted on trucks or skids.

SUMMARY

[0005] The invention includes an apparatus for pumping a fluid through a reciprocating pump. Several motors are responsible for operating the pump assembly. Each of the motors has a drive shaft. The motor drive shafts are connected to a series of drive gears. The drive gears are operably connected to a single driven gear for rotating the driven gear. The single driven gear connects with the pump assembly and drives the reciprocating pump in order to force fluid through the reciprocating pump.

[0006] In one embodiment of many possible embodiments, the motors are located on one side of a longitudinal center line of the pump, and the gears are located on the opposite side of the longitudinal centerline. The motor shafts extending from the motors are parallel to each other and are perpendicular to the longitudinal centerline of the pump.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 is a side elevational view of the reciprocating pump assembly constructed in accordance with the present invention.

[0008]FIG. 2 is a front elevational view of the reciprocating pump assembly shown in FIG. 1.

[0009]FIG. 3 is a top plan elevational view of the reciprocating pump assembly shown in FIG. 1.

[0010]FIG. 4 is a schematic view of the gear assembly for the reciprocating pump assembly shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0011] Referring to FIG. 1, a reciprocating pump assembly 11 includes a pump housing 13, which encloses a crankshaft (not shown) and a crosshead (not shown) of reciprocating pump assembly 11. Pump housing 13 extends substantially horizontal to the ground or a support surface, and away from the crankshaft (not shown) toward a piston rod housing 15 that encloses a piston rod that is attached to the crosshead. A cylinder 17 is connected to the end of piston rod housing 15 extending away from pump housing 13. A piston (not shown) reciprocates to pump fluids through cylinder 17. In the preferred embodiment, the crankshaft (not shown) drives three pistons (not shown) for pumping fluid through three cylinders 17. While depicted as a triplex with three cylinders 17, as will be readily apparent to those skilled in the art, pump assembly 11 can alternatively also have different numbers of cylinders, such as five cylinders. In the preferred embodiment, a common intake manifold 19 supplies fluid to be pumped by pump assembly 11. A common exhaust manifold 21 receives the fluid being discharged by pump assembly 11. A skid having a plurality of rails 23, which are connected to reciprocating pump assembly 11 through supports 25, support reciprocating pump assembly 11.

[0012] In the preferred embodiment, a plurality of motors 27, 29 drive reciprocating pump assembly 11. Motors 27, 29 preferably include a forward motor 27 located substantially above pump housing 13 and offset toward cylinder 17, and a rearward motor 29 substantially located above pump housing 13 and offset rearward farther from cylinder 17 than motor 27. As best shown in FIG. 1, motors 27, 29 preferably straddle the portion of piston pump housing 13 that houses the crankshaft (not shown), and are mounted to the top of housing 13. As shown in the top view of FIG. 3, motors 27, 29 are both located on one side of a longitudinal center line 30 passing through pump assembly 11.

[0013] Referring to FIGS. 2 and 3, a single gear assembly 31 is connected to motors 27, 29 for communicating rotational movement from motors 27, 29 to the crankshaft (not shown). Gear assembly 31 is located on the opposite side of centerline 30 from motors 27, 29. A forward motor drive shaft 33 extends from a forward motor 27 toward gear assembly 31, and a rearward motor drive shaft 35 extends from rearward motor 29 toward gear assembly 31. Shafts 33, 35 are parallel to each other and perpendicular to centerline 30. A forward gear shaft 37 extends toward forward motor drive shaft 33, and a rearward gear shaft 39 extends toward rearward motor drive shaft 35. A flexible coupling 41 connects forward motor drive shaft 33 to forward gear shaft 37. Likewise, another flexible coupling 41 connects rearward motor drive shaft 35 with rearward gear shaft 39. Gear assembly 31 receives rotational movement from motors 27, 29 and translates the rotational movement to a single gear shaft 51 (FIG. 4), which drives the crankshaft (not shown) of reciprocating pump assembly 11. In the preferred embodiment, drive shafts 33, 35 connect to gear assembly 31 at an elevation above pump housing 13, and gear assembly 31 translates rotational movement to the crankshaft (not shown) at an elevation substantially the same as pump housing 13.

[0014] Referring to FIG. 4, an inside portion of gear assembly 31 is shown schematically in more detail. In the preferred embodiment, an forward pinion 43 is located on the end of forward gear shaft 37 extending away from coupling 41 (FIG. 3). A rearward pinion 45 is located on the end of rearward gear shaft 39 extending away from the other flexible coupling 41 (FIG. 3). In the preferred embodiment, forward pinion 43 and rearward pinion 45 are at substantially the same elevation and positioned a pre-selected distance apart. In the preferred embodiment, an intermediate gear 47, which is offset and located substantially below forward pinion 43, engages forward pinion 43 so that intermediate gear 47 rotates as forward motor 27 rotates forward gear shaft 37 forward pinion 43. In the preferred embodiment, another intermediate gear 47 is also located substantially below and offset from rearward pinion 45 so that rearward motor 29 rotates rearward pinion 45 and intermediate gear 47. In the preferred embodiment, intermediate gears 47 are located a pre-selected distance apart from each other and are closer together than forward and rearward pinions 43, 45. In the preferred embodiment, intermediate gears 47 are larger in diameter than pinions 43, 45 so that the rotational velocity of intermediate gears 47 is smaller than the rotational velocity of pinions 43, 45.

[0015] A main gear 49, located substantially between and below intermediate gears 47, is engaged by each of intermediate gears 47 so that intermediate gears 47 translate rotational movement to main gear 49 when pinions 43, 45 rotate. In the preferred embodiment, intermediate gear 47 and forward pinion 43 are offset so that the center points of forward pinion 43, intermediate gear 47, and main gear 49 are substantially linear. Rearward pinion 45 and intermediate gear 47 are also offset so that the center points of rearward pinion 45, intermediate gear 47, and main gear 49 align substantially linearly. In the preferred embodiment, the arrangement of pinions 43, 45, intermediate gears 47, and main gear 49 is substantially V-shaped. A gear shaft 51 extends from main gear 49 and connects to the crankshaft (not shown) extending through pump housing 13 for driving pump assembly 11. In the preferred embodiment, main gear 49 is substantially larger than each intermediate gear 47, thereby also reducing the rotational velocity of gear shaft 51 relative to pinions 43, 45.

[0016] In operation, motors 27, 29 receive an electrical current. Motors 27, 29 rotate motor drive shafts 33, 35 extending substantially parallel to each other from motors 27, 29. Flexible couplings 41 connect motor drive shafts 33, 35 to gear shafts 37, 39 extending toward gear assembly 31. Motor drive shafts 33, 35 translate rotational movement from motors 27, 29 to gear shafts 37, 39. Gear shafts 37 and 39 rotate pinions 43, 45, which in turn engage each of their respective intermediate gears 47. As is evident from FIG. 4, the rotational velocity of each intermediate gear 47 is less than the rotational velocity of either pinions 43 or 45. Each intermediate gear 47 engages main gear 49 to translate rotational movement to gear shaft 51. Gear assembly 31, through pinions 43, 45, intermediate gear 47, and main gear 49, translates rotational movement from motors 27, 29, while reducing the rotational speed of gear shaft 51 extending out of gear assembly 31.

[0017] The invention offers important advantages associated with the positioning of the gear unit on the outside of the pump unit rather than inside the pump unit itself. In this respect, the invention provides the pump with a more compact size and lighter weight. It provides easier mobility and transport for use in mobile oil rigs, resulting from the smaller size and lighter weight. The invention would provide for more convenient service to the pump, and thus less spare parts resulting from operation breakdowns. In summary, the invention provides a more efficient and reliable pump assembly that enhances overall performance.

[0018] It should be apparent to those skilled in the art that it is not so limited, but is susceptible to various changes without departing from the scope of the invention. For example, the different arrangement of gears inside of gear assembly 31 could be utilized to perform substantially the same functions of translating rotational movement to the crankshaft (not shown) of reciprocating pump assembly 11 with additional intermediate gears, or a different arrangement of pinions 43, 45 so that they are not substantially V-shaped while still providing enough space for the placement of more than one motor.

[0019] Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the invention. Accordingly, the scope of the present invention should be determined by the following claims and their appropriate legal equivalents. 

That which is claimed is:
 1. An apparatus for pumping a fluid, comprising: a reciprocating pump; a plurality of motors each having a motor shaft; a plurality of drive gears, each of the drive gears being connected to one of the motor shafts; and a driven gear connecting to the pump for driving the pump, each of the drive gears being operably connected to the driven gear for rotating the driven gear.
 2. The apparatus of claim 1, wherein the driven gear has an angular velocity less than the angular velocity of the drive gears.
 3. The apparatus of claim 1, wherein U-joints are positioned at each end of the motor shafts.
 4. The apparatus of claim 1, wherein the pump has a forward end and a rearward end, and wherein one of the motors is closer to the forward end and other of the motors are closer to the rearward end.
 5. The apparatus of claim 1, wherein the motor shafts are parallel to each other and perpendicular to a longitudinal centerline of the pump.
 6. The apparatus of claim 1, wherein the motors are located on one side of a longitudinal centerline of the pump, and the gears are located on the opposite side of the longitudinal centerline.
 7. The apparatus of claim 1, wherein the pump has a housing, and wherein the gears are located exterior to the housing.
 8. A reciprocating pump assembly, comprising: a pump having a crankshaft, a connecting rod, and a piston; a pair of electrical motors mounted side by side, each motor having a drive shaft extending perpendicular to the connecting rod; a gear box having a pair of inputs, each input of the gearbox being connected to one of the drive shafts, the gear box having a single output operatively connected to the crankshaft.
 9. The apparatus of claim 8, wherein U-joints are positioned at each end of the drive shafts.
 10. The apparatus of claim 8, wherein the pump has a forward end and a rearward end, and wherein one motor is closer to the forward end and the other motor is closer to the rearward end.
 11. The apparatus of claim 8, wherein the drive shafts are parallel to each other and perpendicular to a longitudinal centerline of the pump.
 12. The apparatus of claim 8, wherein the motors are located on one side of a longitudinal centerline of the pump, and the gear box is located on the opposite side of the longitudinal centerline.
 13. The apparatus of claim 8, wherein the pump has a housing, and wherein the gear box is located exterior to the housing.
 14. An apparatus for pumping a fluid, comprising: a reciprocating pump; a plurality of motors each having a motor shaft, the motor shafts being parallel to each other and perpendicular to a longitudinal centerline of the pump. a plurality of drive gears, each of the drive gears being connected to one of the motor shafts; and a driven gear connecting to the pump for driving the pump, each of the drive gears being operably connected to the driven gear for rotating the driven gear, wherein the motors are located on one side of the longitudinal centerline of the pump, and the gears are located on the opposite side of the longitudinal centerline. 